1. Field of the Invention
This invention relates to a confocal laser scanning transmission microscope having deflecting elements for deflecting a light beam at a set frequency in a main scanning direction and an auxiliary scanning direction perpendicular to the main scanning direction to irradiate the light beam to a specimen.
2. Related Background Art
In the optical scanning transmission microscope, a light beam converged in a fine spot is deflected in two dimensions by two deflecting elements to cause the light spot to scan the surface of a speciment at high speed, and the reflected light or the transmitted light on the specimen is detected by a photodetector, such as a photomultiplier, to obtain the optical information of the specimen as electric signals (Japanese Patent Laid-Open Publication No. 121022/1986). In this conventional microscope, generation of stray light can be prevented by using a light beam converged in a fine spot to scan a specimen. Furthermore, the optical information of a specimen is provided as electric signals, and the brightness, contrast, etc. of an image can be electrically adjusted while the specimen can be observed on a monitor.
But in the conventional microscope, a number of optical components are required to form a confocal arrangement. And a drawback of this microscope is that the optical system for guiding a transmitted light again to the deflecting element is complicated, and the microscope is accordingly large-sized. The microscope includes such a number of optical components that it is difficult to adjust their alignment.
Another conventional microscope is a confocal scanning light microscope in which the beam is fixed and the specimen is scanned at high speed ("confocal scanning light microscopy with high aperture immersion lenses", Journal of Microscopy, Vol. 117, Pt 2, Nov., 1979, pp. 219 to 232).
This conventional microscope, however, was not practical in the case of a living specimen since the living thing can not safely be vibrated (scanned).